Ham Radio . Magnum Experimentum
Antennas, experiments, engineering and other articles of interest to radio folks.
Experiments confirmed via various real world measurements.
Tame the predictable mast currents found in any j-pole antenna grounding conductive mast using a simple stub. Shown is empirical evidence why this is a problem and a very simple solution all future grounded j-pole antennas should incorporate.
I measured the SWR and Return Loss of a loaner Diamond X50 antenna.
Doyt Hoverman’s 1960s TV antenna design placed over a simple reflector screen provides impressive performance for today’s UHF and VHF-HI television bands.
Will the KX4O version of the 20-10m Asymmetrical Hatted Vertical Dipole work on 6m? Yes, sort of.
Jim (K9YC) Brown’s toroid winding recipes provide a superb RF choke balun for 30-10m using RG316 and a #43 toroid.
The Asymmetrical Hatted Vertical Dipole (AHVD) prototype is an easy to build, portable alternative to other freestanding vertical HF antennas such as the Buddipole.
Yet another 40m Cloud Burner design featuring a folded dipole driven element plus one reflector wire to facilitate 40m NVIS contacts without need of a tall mast. The design uses electric fence posts for support and needs no balun.
Build the venerable Hoverman TV antenna and watch digital broadcast high definition HDTV television this weekend. This version of a HDTV antenna uses amateur radio antenna building techniques to make a lightweight structure.
I had occasion to test four popular amateur radio mobile antennas. Here are the results of SWR and Return Loss of a Diamond SG7900ANMO, Larsen NMO 2/70, Cushcraft CS-270M and Laird QW144.
The traditional collinear J-Pole, aka Super-J, improves the basic J-Pole. Are further improvements possible? By replacing the phasing stub with a simple coil, the answer is yes. The result is the Collinear J-Pole.
Basic tests of the LNR Precision EF-10/20/40 multi-band portable HF EFHW antenna including S11, SWR and a bandwidth check of the match box.
Return Loss and SWR measurements of a permanent 2m whip installation mid-roof of a Ford Taurus. The effect of doors is shown.
Real measured data reveal the UHF (PL259 and SO239) connectors have real limitations.
Lab tests show post WW2 connector designs perform exceptionally well up to 500 MHz. The SMA, BNC, TNC and N connectors are great.
We pit the PL-259 (and SO-239) against more recent connectors. This is the list of contenders plus a description of the test setup.
The MFJ Analyzer products make easy work of tuning a coaxial quarter wave stub.
Test results of the Coaxial Cable Balun and the Folded Balun (aka Pawsey Stub) reveal coax Velocity Factor applies to the former, but not the latter, unlike what many web sites would have you believe. Part 2 of 2.
Test results show coaxial cable velocity factor does not always enter into stub length calculations especially in the world of Baluns. Part 1 of 2.